1. Field of the Invention
The present invention generally relates to measuring the dimensions of objects such as precious stones and, more particularly, is concerned with a device for precisely and directly measuring a characteristic of an object such as the table facet of a diamond.
2. Description of the Prior Art
Gems such as diamonds have for centuries been viewed as prized possessions. The value of a gem is affected by many factors, including its color, cut, clarity and carat weight. In order to appraise its value, it is necessary for gem dealers and consumers to closely examine a gem. The narrow edge of a gem at its widest part is commonly referred to as the gem girdle. The gem pavilion is the portion below the girdle and the gem crown is the portion above the girdle. A table facet is found in the form of a flat surface on the crown. The table is the largest facet on a cut gem.
The table percentage of the girdle diameter is one of the important factors considered in the valuation of a gem. The longest table measurement is divided by the average girdle diameter to determine what is referred to as the table percentage. Gem dealers and consumers look to this percentage as a way to place value on a gem.
A problem exists, however, in accurately measuring the table facet of a gem. Up until now, the most common method for measuring gems has been holding a transparent millimeter ruler in one hand over a gem held by tweezers in the other hand. The dexterity required, however, to hold a gem by tweezers or some other manual stone holder while measuring the table facet, is too great for many people who find that their hands shake too much to permit the proper alignment of the gem and measuring device.
Devices have been developed over the years for the examination of precious stones. Representative examples are disclosed in U.S. Pat. No. 1,001,991 to Sale, U.S. Pat. No. 1,700,496 to Heitzler, U.S. Pat. No. 3,610,756 to Lenzen et al., U.S. Pat. No. 3,765,775 to Ganssle et al., U.S. Pat. No. 4,265,476 to Elgart, U.S. Pat. No. 4,460,211 to Pomeroy, U.S. Pat. No. 4,508,449 to Okazaki, U.S. Pat. No. 4,906,083 to Sattler, U.S. Pat. No. 5,064,281 to Davis and U.S. Pat. No. 5,306,467 to Douglas-Hamilton et al. Many of these devices, however, are for identification or for determining the color or optical density of a stone, and are not specifically adaptable to taking measurements of the table facets of gems.
Consequently, a need still exists for a device that directly enables the user to accurately measure the table facet and other areas of a gem in order to determine the value of the stone.